In the field of diagnostic analyses various techniques are known to verify the presence of pathogenic organisms and micro-organisms in a biological sample, to classify and/or identify the type and to identify a group of antibiotics able to stop their proliferation in various parts of the human body. This latter operation is technically called antibiogram.
Known techniques to carry out the antibiogram provide to verify the functionality of the antibiotics in suspensions of isolated bacteria and therefore presuppose preventive and long isolation methods, to which the time required for the subsequent verification of the functionality of the antibiotics must also be added. The known methods of bacteria identification provide analysis techniques of the biochemical type always starting from isolated colonies.
The time needed to carry out culture tests (evaluation of bacterial growth), to identify and carry out the antibiogram is long, particularly for serious infections, and this can be dangerous for the patient. It is therefore common for physicians to administer in advance to the patient, without the support of diagnostic tests and exclusively according to a clinical suspicion, a broad-spectrum antibiotic to allow the therapy to be started immediately. The indiscriminate use of such antibiotics induces the so-called phenomenon of drug resistance. One disadvantage deriving from the use of such broad-spectrum antibiotics consists, for example, of the fact that, although such drugs are initially effective against bacterial growth, it may happen that not only are they not able to completely eradicate all the bacterial colonies, but even the surviving bacteria become resistant to the antibiotic chosen by means of genetic mutation and subsequently they proliferate, thus increasing the infection.
The scientific publication by Barnes et al., in the Journal of Clinical Microbiology Vol. 12, No. 4, October 1980 entitled “Clinical Evaluation of Automated Antibiotic Susceptibility Testing with the MS-2 System” is known: it describes an automated antibiotic susceptibility analysis starting from bacteria preliminarily isolated in Petri dishes, or discs. However, obtaining isolated bacteria provides that the sowing has already been carried out, manually or automatically. Moreover Barnes et al. provides a manual visual adjustment by the operator of the desired McFarland turbidity value and uses pre-selected cartridges to carry out the antibiogram.
A solution to the above mentioned disadvantages was proposed in the patent application WO-A-2006/021519 in the name of the present Applicant. This solution, although it is extremely effective in that it allows to obtain an indication of positivity of a sample and the selection of an effective family of antibiotics in a short time, has shown that it can be improved in terms of recognizing and isolating the type of germs or bacterium present in the positive sample.
In particular, purpose of the present invention is to offer a type of complete and automated bacteriological examination, particularly to perform the bacterial growth and the antibiogram, which allows on the one hand to obtain a quick and sufficiently reliable result and on the other hand to have a confirmation of the results with traditional methods, in a completely automated way, that is, reducing to a minimum the intervention of the operator, with obvious operating advantages starting with the taking of the initial sample.
The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.